O-GlcNAcylation mediates the control of cytosolic phosphoenolpyruvate carboxykinase activity via Pgc1?.

ABSTRACT: PGC1? is a coactivator of many transcription factors and cytosolic phosphoenolpyruvate carboxykinase (PCK1) is a key enzyme for gluconeogenesis. PGC1? interacts with the transcription factor PPAR? to stimulate PCK1 expression and thus de novo glucose synthesis. These proteins are not only important for central energy metabolism but also for supplying intermediates for other metabolic pathways, including lipidogenesis and protein synthesis and might therefore be important factors in the ethiopathogenesis of metabolic disorders like diabetes but also in other pathologies like cancer. Since polymorphisms in these proteins have been related to some phenotypic traits in animals like pigs and PGC1? G482S polymorphism increases fat deposition in humans, we have investigated the molecular basis of such effects focusing on a commonly studied polymorphism in pig Pgc1?, which changes a cysteine at position 430 (WT) of the protein to a serine (C430S). Biochemical analyses show that Pgc1? WT stimulates higher expression of human PCK1 in HEK293T and HepG2 cells. Paradoxically, Pgc1? WT is less stable than Pgc1? p.C430S in HEK293T cells. However, the study of different post-translational modifications shows a higher O-GlcNAcylation level of Pgc1? p.C430S. This higher O-GlcNAcylation level significantly decreases the interaction between Pgc1? and PPAR? demonstrating the importance of post-translational glycosylation of PGC1? in the regulation of PCK1 activity. This, furthermore, could explain at least in part the observed epistatic effects between PGC1? and PCK1 in pigs.

SUBMITTER: Latorre P 

PROVIDER: S-EPMC5482481 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature